The present invention relates to methods for assembling and installing an antenna; in particular, for mobile radios.
Known mobile radio antennas are, by way of example, integrated antennas which are matched to the housing inner wall of a mobile radio and, thus, are not visually evident externally. These integrated antennas, which are relatively costly to produce, have the disadvantage that their transmission/reception efficiency is generally poorer than that of a helical antenna; in particular, when the volume of the integrated antenna is restricted. For a given rechargeable battery capacity, this results in a reduction in the period of operation between two charging processes, or requires a correspondingly greater rechargeable battery capacity for the same period of operation. In the same way, a connection to the base station can be terminated prematurely. Furthermore, it is possible for it not to be feasible to produce the integrated antennas in such integrated form if the bandwidth requirements are extreme.
Mobile radio antennas in the form of helical antennas are also known. These antennas are produced essentially from wire and include a transmitting and receiving part that is wound in a helical shape (the helical part), and a contact-making part which is coupled to a printed circuit board assembly in the mobile radio in order to transmit the transmission/reception power.
Although known helical antennas are costly to produce, since the shaping of a contact-making part can be achieved only by repeated three-dimensional bending of the wire, they are widely used.
Moreover, the automatic supply of the helical antennas, such as for assembly of a mobile radio telephone, is made more difficult by the fact that the antennas tend to become jammed when supplied as individual items so that they can be separated only with difficulty, if at all, in an automated manner.
A radio antenna which has a protective housing, is mechanically robust and makes contact with a printed circuit board is known from EP-A2 0 982 794. A multiband antenna is known from European Patent Application EP-A2 0 987 788, which contains a first conductor, which is wound in the form of a helix, and a second conductor, which is in the form of a short rod and which is in turn fitted to the free end of the helix.
WO 99/31756 A1 describes an antenna for transmitting and receiving radio frequency signals in the form of a cylindrical coil with different areas in which the separations differ.
In light of the above, the present invention is directed toward providing low-cost and simplified methods for assembling and installing an antenna.
First of all, a prior art helical antenna is illustrated, for example, in FIGS. 8A and 8B. This helical antenna includes a transmitting/receiving part and a contact-making part. The contact-making part differs considerably from a rotationally symmetrical part, which could assume any position when placed down on a flat surface. In fact, the orientation of a component according to the prior art is governed by the asymmetric shape of the contact-making part and results in the described difficulties in feeding such a component to an assembly process and in using a handling appliance to pick it up.
Conversely, the installation of a helical antenna is considered for the present invention, wherein the helical antenna is produced exclusively or predominantly by a winding and/or turning process. Winding processes such as these are used, for example, for producing tension springs.
An advantage of the pressure contact with the twisted contact-making part of the inventive helical antenna is that there is no need to orient the rotation position for assembly. Furthermore, any desired spring stiffness easily can be produced for the helical antenna by appropriate configuration of the wire diameter, the diameter of the turns and the number of turns which are arranged close to one another. A pressure contact is achieved easily and permanently, despite the shape and orientation tolerance of the partners between which contact is to be made.
A further advantage of the helical antenna of the present invention is that a wound-on terminating ring at the upper end of the helix results in advantageous transmission and reception characteristics.
One major feature of the contact-making part of the helical antenna as produced by the winding technique is that the turns also make direct electrical contact with one another when in the state when contact is made. This is achieved by the turns being produced such that they rest against one another in a prestressed manner. If this is not ensured, then the transmission and reception quality of the antenna may become poorer.
Yet a further advantage of the helical antenna form used is that the helical antenna can be moved directly into flexible plastic tubes via an automatic winding machine, which on the one hand can prevent damage, for example when transported as individual items, and on the other hand can offer the helical antennas in the correct orientation to an automatic assembly machine. As such, for example, there is no need for the conventional vibration helical feed systems for automatic assembly machines.
Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and Figures.